Driving mechanism



20 celeration.

Patented June 2.7, 1933 .UNrrED STATES PATENT OFFICE HENRY W. N IEMAN, OF BETHLEHEM, PENNSYLVANIA, ASSIGNOB TO BETHLEHEM STEEL COMPANY, A. CORPORATION OIE PENNSYLVANIA DRIVING MECHANISH appucauon mea septemer 1a, 1929. serial no. 392,053.

My invention relates to driving mechaj nisms for machines from a suitable source of power. One of the purposes of my invention is a 5 power transmitting mechanism which will furnish a non-varying connection between the driver and the work.

Another objectl is .a device which will give a cushioned start, that is a start which is 10, gradual and does not involve any abrupt transitions. 1

Another object is a transmitting mechanism which is uniform during starting and during its operation, that is to say, a transmitter which will act in the same manner time after time, whether starting, or running continuously.

Another object is a starting mechanism which will have a definite, predetermined ac- Still another object, and one which is decidedly important, is a mechanism which may be readily stopped at any time and an adjustment or other operation of the machine be made by simple manual or other control and yet with an input of power from the source of power. In other words, this object of my invention involves a mechanism whereby-the ordinary drive of the machine may be stopped and an operator controlled operation substituted, but still-with a power input.

My invention can probably be best understood after presenting a specific example of a mechanism embodying its principles.v

Accordingly reference is made to the accompanying drawing which illustrates such .an example:

Fig. 1 is a longitudinal'section;

Fig. 2 is a cross section taken on the line The device comprises work shaft 12, which 1s adapted be operatively connectedto the work; a drlving rum 14 continually being rotated, durin use of the device, from a suitable source o power; a control shaft 11; a system of friction bands 19 arranged in close proximity to the inside cylindricalsurface of drum 14, one end of which system is connected to the control shaft and the other end to the work shaft. Upon applying a torque to the control shaft in a direction the sameas that of the rotation of drum 14, band system 19 frictionally engages drum 14 and a torque in the same direction as the torque applied' to the control shaft is exerted upon the work sha-ft but with greatly increased amplification. Torsion spring 36, connected at one end to the control shaft 11 and at the other end to work shaft 12, exerts a torque on the control shaft to eEect-frictional engagement of band system 19 and drum 14 with the resultant tunning of work shaft 12 with amplilied torque. As the angular movement of the work shaft corresponds to the angular movement of the control shaft, spring 36 will continue to exert a torque on the control shaft with the resulting continuous'driving of the work shaft. Mounted' on control shaft 11 is a brake wheel 41 whereby the torque exertion of spring 36 may be nullified. With this braking means in operation, and the effect of torsion spring 36 thus temporarily eliminated, control shaft 11 may be manually operated .by means of handwheel 35 to produce any desired adjustment or controlled operation of the machine or other work connected to the work shaft 12. Y

Now directing attention to the detail structure and operation of this device: Control shaft 11 is mounted within hollow work shaft 12, which latter is pivotally mounted in su ports 13. Drum 14, which, during use of t e machine, is adapted to be continuously rotated from 4a suitable source of power through the intermediary of gear 15, is rotatably mounted on Work shaft 12.

Fixed to control shaft 11 is arm 16 which extends through an opening 17 in work shaft 12, this opening being somewhat greater than the width of arm 16 to permit of a limited 100 angular motion of control shaft 11 relative to work shaft 12.

Fixed to work shaft 12 is arm 18. These .two arms 16 and 18 are connected at their outer extremities to the ends of friction de- 'vice 19 by which the work shaft is driven from drum 14. This friction device will now be described.

Device 19 comprises two spaced curved bands 20 of steel straps 21, providedwith facings 22 of friction material, and an intermediate band 23 similar to bands 20, comprisin a steel strap 24 provided with a facing 25 of riction material. Ends 26 of bands 20 are oined by bridge 27 to the middle portion of which one end 28 of intermediate band 23 is secured. The other end 29 of band'23 is provided with a hole 30 to receive pin 31 at the outer end of arm 16 secured to the control shaft. The remaining ends 32`of bands 20 are provided with holes 33 adapted to receive spaced pins 34 of arm 18 secured to the work shaft. It will be seen that device 19 extends from its connection with arm 16 nearly acomplete turn of drum 14, as band 23; thence from bridge 27, as bands 20, itextends nearly another complete turn, terminating in the connection of bands 20 to arm 18; in all, nearly two complete turns of the inner cylindrical bearing surface of drum 14. Bands 20 are spaced a sufficient distance apart to allow an appreciable spacing between these bands and band 23 to prevent lateral contact be` tween the bands.

This frictional device 19 is adapted to frictionally engage, through its facings of friction material, the inner cylindrical bearing surface 14 of'drum14.

Fixed to controlshaft 11 is handwheel 35. Torsion spring 36 is attached at one end to hub of wheel 35 and at the other end to disc 37 provided with the ratchet 38 adapted to engage pawl 39 on disc 40 secured to work shaft 12. Secured to control shaft 11 is 45 brake disc 41 which is adapted to be engaged by the friction face 42 on an arm of the braking lever 43, adapted to be operated in any suitable way. Work shaft 12 carries gear 45 to constitute an operative connection between the work shaft and thework.

The operation of the mechanism is very simple. Looking at Fig. 2, assume that the relative positions of friction device 19 and drum 14 are such that the frictional engagement is very slight, and such that as drum 14 revolves in the direction of arrow a, there is practically free slippage. Next assume that control shaft 11 is turned in a counter-clockwise direction, that is in the same direction as drum 14 is continually revolving. During this movement of controlshaft 11 friction device 19 will be pressed into engagement with bearing surface 14 and work shaft 12 65 will be turned in the same angle as the control shaft but with a greatly amplified -torque thereover. Whatever the angle lthrough which the control shaft is turned or the angular velocity thereof there will be a corresponding angle and angular velocity of the Work shaft, but the torque exerted by the work shaft will be much greater than that exerted upon the control shaft.

Now by means of torsion spring 36 a continually acting torque may be applied to control shaft 11. Spring 36 through shaft 11 and arm 16 presses devlce 19 into frictional engagement with drum 14. Naturally the movement of the control shaft coincidental with the exertion of torque thereon by the spring is accompanied by a corresponding movement of arm 18 and the work shaft but with an augmented torque because of the energy furnished by the rotating drum 14. Because of Ythis coincidental movement of the work shaft with the control shaft torsion spring 36 will continue to exert a torque on the control shaft. In other words the torsion spring being connected to both the control and work shafts will maintain a continuous torque on the control shaft so long as the action of such spring is not eliminated in some way.

To be effective spring 36 must exert a torque in such amount that the product of this torque and the amount of amplification secured by drum 14 and band system 19 is greater than the work required of the work shaft. It is clear that as the torsional force of sp1-,ing 36 is varied there will be a correspondingly different torque applied to the control shaft. The greater the torsional force of spring 36 the greater the intensity of frictional engagement of friction device 19 with surface 14 of drum 14. By means of ratchet 38 and pawl 39 it is possible to vary the torsion of spring 36 and thereby secure the desired torque on control shaft 11.

As a result of the product of the torque on the control shaft and the amplification beiner greater than the work required-of the wor shaft, the device, when in operation, will be positive in driving action and there can be no slippage. The device may be easily stopped by rendering the action of spring 36 ineffective. An easy way of accomplishing this is by the application of brake lever 43 to brake drum 41. Obviously Abut a slight application of force is required for this end. Hence the device may be very easily started or stopped.

While the brake is on, control shaft 11 ma be easily operated by hand. By turning han wheel 35 in the direction of rotation of drum -14 corresponding movements may be secured mean the movement of a piece'of machinery for the purpose ofmaking an adjustment or replacement, to start the feed of material through rolls or the like, to free the machine from Jammed material, to observe the action of working parts, and for other reasons. Light machinery may be ini-hed by hand, but in larger apparatus, that requiring upwards of a horsepower drive, hand inching is unsatisfactory. The muscular exertion necessary is not only a severe strain on the operator, but also interferes with close observation, accuracy of adjustment and rapid work. In heavy machinery inching must be done by power, which means turning an electric switch on and off rapidly, or throwing a clutch in and out repeatedly, etc.; and none of these methods affords complete and accurate control of the machinery. In my device, inching does not involve throwing of levers or switches, or the manipulation of belts or clutches; the operator merely takes hold of the handwheel and, with negligible muscular exertion, turns it. The driving motor supplies the energy, while the operator supplies the control. follows the movement of the handwheel whether this movement is fast or slow. The essential characteristic of this feature is the smooth operation of the machine, following exactly the movements of the operator, which movements may be applied easily and therefore accurately fulfill the will of the operator.

Another important feature of m device is what may be designated as the cushioned start. By this expression it is meant that the machine may be started gradually and without abruptness or any sudden or irregular transitions. To secure this property it is necessary that the control shaft have a substantial amount of inertia. The greater the inertia of the control shaft the greater the retardation of the start. The principal factors, practically, in determining the parl -ticular acceleration of start are the inertia of the control shaft and the strength of spring 36. For a particular strength. of spring the desired retardation of start canbe secured by the use of a particular inertiaof the control shaft. A convenient way of securing this result is by employing a handwheel of such mass as will give the control shaft the proper amount of inertia.

Having thus described my invention. what L" I claim as new and desire to secure by Leti shaft, manual means for operating the con The driven machine smoothlyv work shaft, including a flexible friction member adapted to wrappingly engage the power driven rotating member with an intensity of frictional lengagement varying with the amount of torque exerted on the control shaft, manual means for o erating the control shaft, and means connecting the control shaft and work shaft for maintaining a continuous torque on the control shaft.

3. In a driving mechanism, a control shaft, a work shaft, a power driven rotating member, means connecting the control shaft and work shaft including a flexible friction member adapted to wrappingly engage the power driven rotating member with an intensity of frictional engagement varying with the amount of torque exerted on the control shaft, manual means for operating the control shaft, and resilient means connecting the control shaft and work shaft for maintaining a continuous torque on the controlshaft.

4. In a driving mechanism, a control shaft, a work shaft, a power driven rotating member, means connecting the control shaft and the work shaft including a flexible friction member adapted to wrappingly engage the power driven rotating member with an intensity of frictional engagement varying with y the amount of torque exerted on the control shaft, and means .for maintaining a continuous torque on the control shaft, said control shaft being provided with means hav ing such inertia as to give a predetermined desired retardation of start.

5. In a driving mechanism, a control shaft, a work shaft, a power driven rotating member, means connecting the control shaft and the work shaft including a flexible friction member adapted to wrappingly engage the power driven rotating member with an in-y tensity of frictional engagement varyin g with the amount of torque exerted on the control shaft, and means for maintaining a continnous torque on the control shaft, said control shaft being provided with means having such inertia. Vand said torque maintaining means exerting such a torque as to give a predetermined desiredg'etardation of start.

6. In a driving mechanism, a control shaft,` a work shaft, apower driven rotating member, means connecting the control shaft and the work shaft-including a flexible friction member adapted to wrappingly engage the power driven rotating member with an intensity of frictional engagement varying with the amount of torque exerted on the control shaft, manual means for operating the controlshaft, means for maintaining a continuous torque on the control shaft, and means Lber, means connecting the control shaft and work shaft including a flexible friction member adapted to wrappingly engage the power driven rotating` member with an intensity of frictional engagement varying with the amount of torque exerted on the control shaft, means for maintaining a continuous torque on the control shaft, means for rendering such last mentioned means ineffective, said control shaft being provided with means having such inertia as to give a predetermined desired retardation of start.

8. In a driving mechanism, a control shaft, a work shaft, a power driven rotating member, means connecting the control shaftl and the work shaft, including a flexible friction member adapted to wrappingly engage the power driven rotating member with an intensity of frictional engagement varying with the amount of torque exerted on the control shaft, manual means for operating the control shaft, means for maintaining a continuous torque on the control shaft, means for varying the amount of such maintained torque on the control shaft and means for rendering such torque maintaining means ineffective.

9. In a driving mechanism, a control shaft, a work shaft, a powerdriven rotating member, means connecting the control shaft and the work shaft, including a flexible friction member adapted to wrappingly engage the power driven rotating member with an intensity of frictional engagement varying with the amount of torque exerted on the control shaft, means for maintaining a continuous torque on the control shaft, means for varying the amount of such maintained torque on the control shaft and means for rendering such torque maintaining means ineffective, said control shaft being provided with means having such inertia as to give a predetermined desired retardation of start.

10. In a. driving mechanism, a control shaft, a work shaft, a power driven'rotating member, means connecting the control shaft and the work shaft including a iexible friction member adapted to Wrappingly engage the power driven rotating member with an intensity of frictional engagement varying with the amount of torque exerted on the control shaft, and means for maintaining a -continuous torque on the control shaft, means for rendering such torque maintaining means ineffective, and means under the direct control of the operator for applying torque to the control shaft when such torque maintaining means are ineffective.

11. In a driving mechanism, a control shaft, a work shaft, a power driven rotating member, means connecting the control shaft and' signature.

HENRY W. NIEMAN. 

